In magnetic storage devices such as hard disk drives (HDD), read and write heads are used to magnetically read and write information to and from storage media, such as a magnetic storage disk. A HDD may include a rotary actuator, a suspension mounted on an arm of the rotary actuator, and a slider bonded to the suspension to form a head gimbal assembly. In a traditional HDD, the slider carries a write head and read head, and radially flies over the surface of the storage media.
A Heat Assisted Magnetic Recording (HAMR) device is an enhanced HDD that applies heat to magnetically soften the media surface during recording, particularly useful for high capacity storage with physically smaller bit sizes. The heat may be generated by a laser coupled to a waveguide and a transducer formed on the slider. The slider is a base on which the read and write heads are mounted on a trailing edge surface that is perpendicular to the air bearing surface (ABS). The magnetic media surface is exposed to the ABS during read and write operation. The waveguide extends through the back side of the slider and is directly coupled to a laser from an external source. A lap-and-look lapping process performed on the back side of the slider during fabrication of the HAMR device may not consistently provide optimum control of the dimension between the waveguide with respect to the back side surface of the slider for coupling the waveguide to the laser.